Process of extracting bromin from brine.



Nd.'7l4,l60. 'Phfented Nov. 25, I902.

H. H. now. PROCESS OF EXTBACTING BBOMIN FROM BRINE.

m lm'zion filed Dec. 7, 1900 (No Model.)

INVENTOI? Jfjf (QM 7 ATTORNEY.

WITNESSES UNITED STATES v PATENT OFrioE.

HERBERT H. DOIV, OF MIDLAND, MICHIGAN, ASSIGNOR TO THE DOW CHEMICALCOMPANY, OF MIDLAND, MICHIGAN, A CORPORATION OF MICHIGAN.

PROCESS OF EXTRACTING BROMIN FROM BRINE.

SPECIFICATION forming part of Letters Patent No. 714,160, datedNovember25, 1902.

Application filed December 7. 1900.

To all whom, it may concern:

Beit known that I, HERBERT I-I. DOW, a citizen of the United States, anda residentofMidland, county of Midland, State of Michigan, have inventeda new and useful Improvement in Processes of Extracting Bromin fromBrine, of which the following is a specification, the principle of theinvention being herein explained and the best mode in which I havecontemplated applying that principle, so as to distinguish it from otherinventions.

My invention consists in an improved process for more completelyextracting bromin from natural bromid brines and the production of abromid nearly or entirely free from chlorin. Said process consists of aseries of steps hereinafter fully described.

The annexed drawing and the following description set forth in detailone mode of carrying out the invention, such disclosed meansconstituting but one'of various ways in which the principle of theinvention may be used.

In said annexed drawing is represented a diagrammatic view of a form ofapparatus used in my improved process.

In said apparatus, A represents a brine-reservoir of a main system,which reservoir is supplied with brine from an auxiliary system. Thesetwo systems and their connection with each other will now be described.

The brine is permitted to flow from the said reservoir A into anoxidizer B. The oxidation may be accomplished by any one of variousmeans explained in my reissued United States Letters Patent No. 11,232.From the oxidizer the brine fiows into a series of blowout towers C, nospecial form of tower being required, many forms of apparatus forbringing liquids into contact with gases being familiar to technicalchemists. Lunge-plate columns or coke-towers are common exam ples ofapparatus that may be employed for this purpose.

Part of the brine from the reservoir A is permitted to fiow through atailings-tower D, which is connected by means of a gas-passage d withthe oxidizer B. The brine after passing through the tailings-tower ispumped by any suitable means, such as a pump a, into a Serial No.39,042. (No specimens.)

purifier E, consisting of a series of towers of construction similar tothat of the blow-out towers and in which the gas may be brought intointimate contact with the brine flowing therethrough.

From the purifier the brine is pumped through a pipe B into the oxidizerB, so that it is seen all of the brine from the reservoir A eventuallypasses through the oxidizer B. A blower F forces a current of airthrough the blow-out towers C, from whence it emanates through asuitable duct G and passes into the purifiers E, which are connectedwith each other by suitable ducts e. A duct H leads from the purifyingapparatus to a second system of purifiers J of a construction similar tothat of purifiers E. Said purifier J is connected by means of a ductKwith the absorbers L, also of similar construction to blow-out towersO. Said absorbers are connected with the blower E, which forces air intothe blow-out towers O, as shown. It is thus seen that a closed system ofair circulation is established, the above-described apparatusconstituting the main system used in my improved process.

From the blow-out towers O the brine is pumped into an oxidizer M of theauxiliary system, from whence it flows into a system of blow-out towersN of a construction similar to that previously described, and from whichthe brine, which, as will be hereinafter fully described, has beenalmost completely divested of bromin, flows into the waste.

An air-duct 0 leads from the blow-out towers and forms an exit for air,which is drawn through such towers by means of exhaustblower P, as willpresently be seen. Said duct passes into a system of absorbers Q of aconstruction similar to that previously described in the main system. Aconnection is also formed from the blower F to the absorbers Q throughthe connection Z, in which is located a regulating device z.

A second brine-reservorRis connected with said absorbers, the brine fromsuch reservoir flowing through said absorbers and from them into thereservoir A of the main system.

The oxidizer M is provided with a duct 0, which connects with the duct0. The exhaust-blower P is connected, as shown, with the absorbers Q.Oxidizer M, blow-out tower N, absorbers Q,and blower P and theirconnections constitute the auxiliary system of the apparatus.

In order to set free all of the bromin in the brine as shown in theprocess described in my reissued Letters Patent of the United States No.11,232, dated April 12, 1892, it would be necessary to overoxidizeitthat is, oxidize it to such an extent that some free chlorin exists inthe brine. The complete subsequent blowing out of the bromin from thebrine would entail the simultaneous blowing out of the chlorin presentdue to such overoxidation, a condition which could not be allowed toexist contemporarily with the economical manufacture of bromid andbromates, as is well understood. In order to recover practically all ofthe bromi n from the brine treated, with a contemporary expenditure ofoxidizing energy equivalent to the bromin content only, my improvedprocess is carried out in the following manner:

The brine on leaving the reservoir A, as above stated, enters theoxidizer B, where it is oxidized sufficiently to set only part of thecontained bromin free, together with a certain amount of chlorin. Thebrine then leaving said oxidizer enters the blow-out towers 0, throughwhich a current of air is forced by the blower F, such air passing outof the blow-out towers laden with free bromin and chlorin. min andchlorin laden air enters the purifiers E, through which, as previouslydescribed, is flowing a supply of brine from the main reservoir A, whichhas previously passed through the tailings-tower D. The bromin andchlorin laden air passing through the purifiers E comes into contactwith the brine flowing therethrough and is almost completely depleted offree chlorin by the substitution of the latter for the bromin in thebromid present in the brine, the chlorin in the air being thus utilizedto liberate the bromin. We have found in practice, however, that suchchlorin is not completely absorbed from the air.

The nearly-chlorin-free air coming from the purifiers E passes throughthe second set of purifiers J, through which a strong bromid solution(provided from a suitable source, such as the receptacle X) is caused tocirculate, where the last trace of chlorin is removed by thesubstitution of such chlorin for the bromin in the bromid solution, suchbromin being liberated and passing out through the duct K, together withthe free bromin previously formed. Such brominladen air then passes intothe absorbers L, which may contain any suitable material, the latterbeing provided from a suitable source of supply, such as the receptacleY, which will combine with the bromin, as explained in myabove-mentioned Letters Patent.

As above described, the air after having been depleted of its bromin inthe absorbers From the blow-out towers such bro- L is again blownthrough the blow-out towers C, the same process as before described thenbeing repeated in the main system.

The brine in the tailings-tower D is used only to absorb the gasespassing from the main oxidizer-vent 01, such gases consisting mainly ofbromin, formed by oxidation and air. The brine leaving this tower maycontain considerable free bromin and is thence conducted to the purifierand blown out to such a point that the amount of bromin in the air andin this brine are in equilibrium. The brine that leaves the main systemfrom the blow-out towers G contains some free bromin which has not beenblown out by the air-current. It also contains some combined bromin thatwas not oxidized in the main system oxidizer B. In fact, it is necessaryto leave quite an amount of combined bromin in the brine at this stage,as the bromin that is blown out contains less chlorin if some bromid bepresent. This brine after being discharged from the main system passesto the oxidizer M in the auxiliary system, where it is oxidized toexcess in order that all the combined bromin may be converted into freebromin, chlorin being set free by such oxidation, it being practicallyimpossible to set all the bromin free without setting free some chlorin.From said oxidizer M the brine then passes through the blow-out towersN, where practically all the bromin is extracted with a considerableproportion of chlorin. 'This bromin and chlorin laden air is then passedthrough the air-ductO into and through the absorber Q, where thischlorin and bromin are removed by being absorbed by brine, ashereinafter explained, which passes therethrough and is discharged intothe reservoir A of the main system.

All natural brines that contain bromid are extremely impure, in manycases containing besides the chlorid of sodium, calcium, magnesium,potassium, lithium, also carbonate of iron. In other cases they containdissolved hydrogen sulfid and also traces of iodids, and as is wellknown oil is frequently associated with brine in natural deposits. By myimproved process the brine is not evaporated, is not even heated, but isworked in the cold without any preliminary process whatever for thebromin it may containan obvious economical advantage. Any impuritiesthat have a reducing action on bromin will of necessity have to beoxidized before the bromin itself can be set free. It is therefore ofgreat economical value to oxidize as far as possible with atmosphericair, and if this oxidation is then supplemented by the action of wastegases that contain traces of chlorin or bromin a further economicaleffect will result. The greatimportance of the feature will beunderstood when it is considered that natural brines contain in almostevery case very much less than one-tenth of one per cent. of bromin, andhence an enormous amount of brine must be handled in order to secure alimited amount of bromin, and if this brine, as pumped, contains onlytraces of reducing material, and if such material is not removed by suchpreliminary oxidation such reducing material may consume more oxidizingenergy than is consumed in the extraction of the bromin itself aftersuch preliminary oxidation has taken place. In other words, when theoxidation is conducted solely with chlorin or its equivalent and not byair several times the amount of chlorin may be consumed than would bethe chemical equivalent of the bromin produced. As thesebromid-containing brines are always more or less impure, they are notadapted for the manufacture of salt, and if salt be made from suchbrines the impurities seriously complicate the process and deleteriouslyaffeet the quality of the salt manufactured. It is therefore verydesirable to extract the bromin without incurring the necessary expensewhich the manufacture of salt-that is, the evaporation of thebrineinvolves. By the described process bromin is extracted without theproduction of salt, and hence without the application of heat.

The hydrogen sulfid and other impurities are not added or required forthe express purpose of absorbing chlorin, but are necessary evils thatoriginally exist in the brine, which must be gotten rid of before freebromin can exist in the brine; but to the extent that they absorb freebromin in the air with which it it is blown they have value. I amtherefor able to use the natural brine as an absorbent material in thetowers Q.

The hydrogen-sulfid gas contained in the Y natural brine, which flowsinto the absorbers Q, will hence unite'with the free bromin in thechlorin and bromin laden air, which passes therethrough from theblow-out towers N.

The natural-salt brines from the reservoir R entering the top of theabsorbing-towers Q come into contact with air which, entering at thebottom of such towers, has been, as will presently be explained,madepractically pure, and hence more or lessof the gases dissolved in thebrine will be removed. As the brine descends a little lower the hydrogensulfid thathas not been removed by the pure air, as well as any othersubstances capable of oxidation by bromin and which have remained in thebrine, is attacked and destroyed by the oxidizing action of the dilutebromin and chlorin. As the brine descends still lower and becomes freefrom reducing agents the chlorin in the air will set some bromin free,and the bromin itself, to a limited extent, will become dissolved in thebrine, the latter passing to the main system, in which the bulk of thebromin is set free and is blown out. Such above-described union of thehydrogen sulfid and the bromin forms additional bromid, which hencemakes it subsequently necessary to resort to additional oxidation in theoxidizers to recover such combined bromin,

such additional oxidation being proportional to the amount of hydrogensulfid present. Such hydrogen sulfid is, however, blown out to a greateror less extent by the air at the top of absorber Q, and hence ispartially removed before it enters the oxidizing-towers or the oxidizingzone of the auxiliary absorber. The amount of additional oxidationrequired to set the bromin free which has combined with the sulfid ishence greatly reduced.

Carbon dioxid, which may be present in the brine, is likewise removed,and is therefore prevented from retarding absorption in theabsorption-towers J when alkaline hydrate is used as an absorbentmaterial to produce a bromid.

It is thus seen that the excess of oxidizing agent in the form ofchlorin gas which has been necessarily expended in the auxiliaryoxidizer M in order to remove the last traces of bromin is used to setfree in the untreated brine the amount of bromin equivalent to theexcess of oxidizing agent employed, and I am in this manner enabled touse again and again such excess of oxidizing energy first supplied tothe system and, as before stated, to recover practically all the brominfrom the brine treated.

It is evident that a second auxiliary system might be added by takingthe exhaustbrine from the first auxiliary system, oxidizing and blowingit and absorbing the bromin from the bromin-laden air in natural orunoxidized brine, then subsequently substituting this brine for thenatural-brine supply in the auxiliary system, thus making what might becalled a triple-extraction system instead of a compound system. It isalso evident that the process might be carried to a fourth or fifthstage. The compound system described is, however, preferable.

The use of the brine in the purifiers E, and the consequent utilizationof the bromid contained therein for absorbing the chlorin, does awaywith the necessity of employing a large quantity of expensive alkalinebromid for this purpose and prolongs the life of such alkaline bromid asis used in the purifiers J by'performing a large part of the Work ofextracting 'chlorin which would otherwise devolve upon such purifiers.

Other modes of applying the principle of my invention may be employedinstead of the one explained, change being made as regards the stepsherein disclosed, provided the step or steps covered by any one of thefollowing claims be employed.

I therefore particularly point out and distinctly claim as myinvention-- 1. The steps in the process of manufacturing bromin frombromid-containing brines, which consist in bringing unoxidizedbromidcontaining brine into contact with air and subsequently intocontact with air containing a free halogen.

2. The steps in the process of manufacturing bromin frombromid-containing brines,

&

which consist in bringing unoxidized bromidcontaining brine into contactwith air and subsequently into contact with air containing chlorin.

3. The steps in the process of manufacturing bromin frombromid-containing brines, which consist in bringing unoxidizedbromidcontaining brine into contact with air and subsequentlyintocontact with air containing bromin and chlorin.

4. The stepsin the process of extracting bromin from bromid-containingbrines, which consist in oxidizing the brines short of the bromidcontent, blowing out the free bromin, and then oxidizing the remainingbrine to excess of the bromid content.

5. The step in the process of manufacturing bromin, which consists inbringing unoxidized bromid-containing brine into contact with aircontaining a free halogen which has been liberated in such process.

6. The step in the process of manufacturing bromin, which consists inbringing'unoxidized bromid-containing brine into contact with aircontaining chlorin which has been liberated in such process.

7. The step in the process of manufacturing bromin, which consistsinbringing unoxidized bromid-containing brine into contact with aircontaining chlorin and bromin which have been liberated in such process.

8. In a process of extracting bromin from bromid-containing brines, themethod of removing traces of chlorin from dilute bromin and chlorinmixtn res, which consists in treating said mixtures to contact with anatural brine-containing bromid, and then to contact with a moreconcentrated bromid solution comparatively free from chlorin.

9. The process of extracting bromin from bromin-containing brines, whichconsists in removing a portion of the bromin, subjecting untreatedbromid-containing brine to the action of chlorin and bromin set free byexcessive oxidation of brine from which such portion of the bromin hasalready been removed whereby the amount of bromin in such untreatedbrine is increased and practically all the bromin in thepreviously-oxidized brine is recovered.

10. The process of extracting bromin from bromid-containing brines whichconsists in oxidizing the brine, blowing out the bromin and chlorin soformed with air, treating the bromin and chlorin laden air withbromid-containing brine whereby most of such chlorin isremoved,subsequently absorbing the remaining chlorin wherebychlorin-free air is obtained, oxidizing the brine recovered from theblowing-out process to excess and treating unoxidized brine with thechlorin and bromin formed by such excessive oxidation whereby the amountof bromid in such brine is increased.

Signed by me this 5th day of December, 1900.

HERBERT H. DOW.

Attest:

E. E. CRowELL, A. E. MERKEL.

